Ram with cushioned piston stroke

ABSTRACT

A ram with a construction for cushioning the ram&#39;&#39;s piston as it nears the end of a stroke while accommodating a fast return stroke in the piston. A metallic piston ring is loosely mounted to permit limited axial movement within an annular groove on the piston. A fluid passage connects this groove with an end of the piston. The ring on movement of the piston toward the end of a stroke moves to a position tending to close off the fluid passage, to capture cushioning fluid. With pressure fluid admitted to the ram to produce a return stroke, the ring shifts axially to a position tending to open up the fluid passage.

D United States Patent n 3,592,106

[72] Inventor Gaylord G. Baughmln 3,296,942 l/l967 Nelson 92/85 XTroutdlle. OYIg- 3,329,068 7/l967 Klaus 92/85 X [Zll Appl No. 836.5333.364.675 l/l968 Dorer 92/162 X [22] Filed June 25. 1969 3,388,6346/1968 Madland 91/409 X g ZL Primary Examiner-martin P, SchwadronPoland, Assistant EXflfl'iUlCf- Lazarus Anomey- Kohsch & Hartwell [54]RAM WITH CUSHIONED PISTON STROKE 7CW3Dr-hg Fm ABSTRACT: A ram with aconstruction for cushioning the rams piston as it nears the end of astroke while accommodat- [52] US. Cl 92/85, i a f return t k i th i t At ni i t i i 9l/409 loosely mounted to permit limited axial movementwithin an [5|] IIILCI Fold 11/02 m groove on the piston A fl id passageconnects this surd 92/853 groove with an end of the piston. The ring onmovement of the 9l/408- 405 piston toward the end of a stroke moves to aposition tending to close off the fluid assa e, to ca lure cushioninfluid. With Helena cued pressure fluid admittzd to the ram to produce are turn stroke, UNITED STATES PATENTS the ring shifts axially to aposition tending to open up the fluid 2,935.04? 5/1960 Ortman et a191/408 X passage.

PATENTEUJuu 2:911 3.592.106

Gaylord GBaughmcm INVENTOR BY xMd. Mum

RAM WITH CUSHIONED PISTON STROKE This invention relates generally tofluid-operated piston cylinder devices, also referred to herein forbrevitys sake as rams, provided with a construction for cushioning therams piston on such nearing the end of a stroke and for providing a fastreturn stroke in the piston when such is subsequently cy cled in theopposite direction.

Where a piston is permitted to complete a full stroke against the endwall of a cylinder, without being earlier stopped or slowed down, animpact is produced which shortens the life of the ram, produces noise,and results in other undesirable features. To prevent such fromoccurring, it has been the practice to provide a construction wherein aportion of the fluid within the cylinder which is being expelled by thepiston on a stroke be captured within an end wall region of the ram asthe piston nears the end of its stroke, with further movement of thepiston being accompanied with metered flow of this fluid from such endwall region through a metering passage. If the piston is to have a fastreturn stroke on moving in the opposite direction, there must beprovided some means for the quick introduction of a significant volumeof fluid into this end wall region. If flow into this region ispermitted only through the metering passage which produces thecushioning action, obvi ously return movement of the piston at leastduring the start of its return stroke will be rather slow. To obviatethis difficulty, various approaches have been taken, including theprovision of a ball-check valve which closes when cushioning is beingproduced and which opens to provide an alternate route for the inflow offluid on the return stroke of the piston.

Generally, an object of this invention is to provide an improvedconstruction for cushioning the piston and for permitting a fast returnstroke, which is relatively simple, and per mits the elimination ofball-check valves and the like, which tend to complicate theconstruction of the ram, and have other disadvantages, such as beingbulky, subject to wear, etc.

A more specific object of the invention is to provide such aconstruction wherein a valving action is provided controlling flow tothe region in a ram which captures fluid for cushioning purposes, by aring mounted on the rams piston which is axially shiftable to a limiteddegree to produce such valving action,

In a preferred embodiment of the invention, the ring takes the form ofthe usual metallic piston ring found in many mechanical applications forsealing the gap between a piston and a cylinder wall,

As contemplated by this invention, and as a further object thereof, adouble-acting ram is provided which includes such axially shiftablerings adjacent opposite ends of the rams piston. Between the ends of thepiston, a fluidtight sealing ring, referred to herein as a sealingannulus, is provided. Providing for the metered flow of fluid aremetering passages which come into play with the piston of the ram movingin a stroke to each ofthe rams opposite ends.

Various other objects and advantages of the invention will become morefully apparent as the following description is read in conjunction withthe accompanying drawings, where:

FIG. I is a view, partially broken away, illustrating the end of a ramas contemplated herein, such being equipped with rings adjacent oppositeends of its piston functioning to con trol flow between the sides of thepiston and regions on opposite ends of the piston adjacent end walls inthe ram (where fluid producing cushioning collects);

FIG. 2 is a view similar to portions of FIG. I, but showing he rings ina different position; and i FIG. 3 is a view on a slightly smaller scaleshowing the ram in its entirety Referring to the drawings, and first ofall more particularly to FIG. 3. here a double-acling fluid pressureoperated ram is shown generally at which includes a ram cylinder I2 and2nd walls [4 and 16 closing off opposite ends of the ram cylinder,Projecting out from one end of the cylinder is a piston rod 18 which ascan be seen in FIGS. I and 2, has the ltl usual piston 20 secured to oneend. Piston 2) is reciprocablr within the cylinder. To move the pistonin a stroke from the right end ofthe ram to the left in FIG. 3, fluid isintroduced to the ram through conduit 22 and exhausted through conduit24, To move the piston and its rod in a return stroke, fluid isintroduced through conduit 24 and exhausted through conduit 22.

Referring more particularly now to FIGS. I and 2, the piston 20 issecured to the end of the rod by a nut 26 which bears against the pistonand is screwed onto threaded end por tion [Bar of the piston rod.Producing a seal between the piston rod and the piston is O-ring 28,with backup rings 29 being provided on either side of ring 28.

A fluidtight seal is produced between the outer periphery of the pistonand the inner wall of the cylinder by O-ring 30, also referred to hereinas a fluidtight sealing annulus. The O-ring together with backup rings32 and rider rings 34 (which may be made of nylon) are all disposedwithin an annular groove 36 provided about the circumference of thepiston approximately midway between its ends.

Considering first of all the left end of the piston in FIGS. I and 2(which faces left end wall 14), adjacent the left end of the piston is agroove 38 which mounts a piston ring shown at 40. The piston ringresembles conventional piston rings, and comprises a split metal ringsealing the gap between the cir cumference of the piston and the insideof cylinder I2. The periphery of the ring, therefore, is radiallyoutwardly of the periphery of the piston and such slides against theinner cylindrical wall ofthe cylinder.

The ring is loosely mounted in groove 36 with some clearance provided onopposite sides, whereby it is axially movable to a limited degree withinthe groove. The clearance need not be great, and actually has beensomewhat exaggerated in the drawing for the purpose of best illustratingthe invention. In FIG. 2, the ring is shown snugly against the side ofgroove 38 which is directly adjacent the left end of the piston, whereasin FIG. I, the ring is shown shifted axially and to the right andagainst the wall of the groove which is more remote from the left end ofthe piston.

A cylindrical recess 42 is shown indented inwardly from the left end ofthe piston. Connecting the base of groove 28 with this recess, andthrough this recess with the region bounded between the left end of theram and end wall I4 such as the region R shown in FIGS. 1 and 2, aremultiple bores 44 which may be equally circumferentially spaced aboutthe piston. These bores and recess 42 collectively constitute fluidpassage means connecting the groove with the recess.

Disposed inwardly from the left end of the piston, and more specificallybetween groove 36 containing O-ring 30 and groove 38, is another annulargroove 46. Connecting the base of this groove with recess 42 is ametering bore or passage 48.

The piston ring illustrated in the drawings, as exemplified by theportion of the ring protruding upwardly from the base of FIG. 2, isprovided with an overlapping end construction, with tongues 40a, 40b atthe ends of the ring overlapping where the split ring comes together.This overlapping construction is effective to give a better seal at thisparticular part of the piston ring. A so-called conventionalsquare-ended split ring may also be utilized, with squared ends comingtogether at the point where the ring is split. The latter construction,however, does not provide as good a seal at this region of the ringv Theright end of the piston in FIGS. 1 and 2 has a construction whichclosely resembles the left end of the piston. Thus, there is provided agroove 50 which loosely mounts a piston ring 52. A cylindrical recess 54is indented inwardly from the left end of the piston. Bores 56constitute a fluid passage means connecting recess 54 with groove 50.Disposed between groove 50 and groove 38 is a groove 58 connectedthrough a metering passage or bore 60 with recess 54.

Conduit 24 connecting with the left end of the ram connects with a port62 which communicates with the inside of the cylinder at a point locatedbetween grooves 36, 38, with the piston adjacent the left end of theram. Conduit 22 at the oposite end of the ram connects with the insideof the cylinder etween grooves 38 and 50 with the piston ad acent theoposite end of the ram.

Explaining the operation of the ram, and assuming that the iston isbeing moved in a stroke from the right to the left end fthe ram in FIG3, fluid is introduced through conduit 22 rid exhausted through conduit24. On the pistonmoving iston ring 40 to the left of port 62 in FIG 1,fluid captured etween the left end wall of the ram and the left end ofthe iston produces a buildup in pressure in the space or region icatedbetween this wall and the left end of the piston, such :gion beingindicated at R in H I. This results in piston ng 40 moving axially tothe right and snugly against the side [groove 38 which is remote fromthe left end of the piston. 'ith the piston ring thrust tightly againstthis side of the 'oove, significant flow of fluid through bores 44 andpast the iston ring to port 62 is prevented. Fluid captured in region R.ierefore, is permitted to exhaust only at a controlled rate troughmetering bore 48. This functions, therefore, to roduce a cushioningaction slowing down the travel of the .ston as it nears end wall 14.

At the start ofa return stroke, and with fluid under pressure imittedthrough conduit 24 and exhausted through conduit 2, such fluid underpressure operates to shift the piston ring i the left, as shown in FIG.2. With the ring in this position, ares 44 accommodate the admission offluid to region R igether with metering bore 48. Fluid under pressure,thereire, rapidly builds up on the left end of the piston, whereby iepiston moves in a return stroke at a rapid rate.

Piston ring 52 operates in a similar fashion, in blocking off ow, and inpermitting on a return stroke rapid inflow of presire fluid, when thepiston is adjacent right end wall 16.

The construction requires no ballcheclt valves or similar :vices forproducing one-way flow between the sides of the iston and the ends ofthe piston. Major modification of the iston, the cylinder, or the endwalls, is not required. The conruction is easily put together, andrepair and replacement of arts is readily facilitated.

While an embodiment of the invention has been described, bviouslychanges and variations are possible as would be aparent to one skilledin the art I claim:

1. In a ram including a cylinder, a piston within the cylinder,

1d an end wall closing off one end of the cylinder, a construe onproviding for cushioning of the piston when it moves in ne direction toa position adjacent said end wall and per itting rapid return movementof the piston when moved in ie opposite direction, comprising an annulargroove extending about the piston including one side which is adjacentand an opposite side which is remote from said end wall,

a ring mounted within said groove with the periphery thereof disposedradially outwardly of the periphery of the piston and against the insideofthe cylinder. said ring being loosely mounted in said groove wherebyit is axially shiftable within the groove,

fluid passage means connecting the end of the piston which faces saidend wall of the cylinder with said groove, and

a port in the ram cylinder for the supply and exhaust offluid to saidram communicating through said groove and said fluid passage means withsaid end of the piston when said piston is adjacent said cylinder endwall and said ring is against said one side of the groove,

said port being closed off from said end of the piston with said ringagainst said opposite side of the groove.

2. The rain of claim I, wherein said piston has a recess indentedinwardly from its said end which faces said end wall, and said fluidpassage means includes said recess. i

3. The ram of claim I, which further comprises metering passagecommunicating with said end of said piston and joining with the side ofthe piston at a point located toward the pistons opposite end from thelocation of said groove.

4 The ram ofclaim 3, wherein a fluidtight sealing annulus is providedwhich extends about said piston and which is located toward saidopposite end of the piston from the point where said metering passagemeans joins with the side of the piston 5 A douhle'acting ram as claimedin claim I, which in cludes an opposite end wall closing off theopposite end of the cylinder, said piston having an end opposite itssaid one end which faces said opposite end wall, another annular grooveextending about the piston adjacent said pistons opposite end, saidother groove including one side which is adjacent and an opposite sidewhich is remote from said opposite end wall, another ring mounted withinsaid other groove with the periphery thereof disposed radially outwardlyof the periphery of the piston and against the inside of the cylinder,said other ring being loosely mounted in said other groove whereby it isaxially shiftable within said other groove, a second fluid passage meansconnecting said opposite end of the piston with said other groove, andanother port in the ram cylinder for the supply and exhaust of fluid tosaid ram, said other port communicating through said other groove andsaid second fluid passage means with said opposite end of the pistonwhen said piston is adjacent said opposite cylinder end wall and saidring is against said one side of the other groove, said port beingclosed ofi from said opposite end of the piston with said ring againstsaid opposite side of said other groove.

6. The ram of claim 5, which further comprises a fluidtight sealingannulus extending about the piston at a location inter mediate saidfirst and said other groove 7. The ram of claim 6, which furthercomprises metering passage means communicating with said opposite end ofthe piston and joining with the side of the piston at a point locatedbetween said annulus and said other groove.

1. In a ram including a cylinder, a piston within the cylinder, and anend wall closing off one end of the cylinder, a construction providingfor cushioning of the piston when it moves in one direction to aposition adjacent said end wall and permitting rapid return movement ofthe piston when moved in the opposite direction, comprising an annulargroove extending about the piston including one side which is adjacentand an opposite side which is remote from said end wall, a ring mountedwithin said groove with the periphery thereof disposed radiallyoutwardly of the periphery of the piston and against the inside of thecylinder, said ring being loosely mounted in said groove whereby it isaxially shiftable within the groove, fluid passage means connecting theend of the piston which faces said end wall of the cylinder with saidgroove, and a port in the ram cylinder for the supply and exhaust offluid to said ram communicating through said groove and said fluidpassage means with said end of the piston when said piston is adjacentsaid cylinder end wall and said ring is against said one side of thegroove, said port being closed off from said end of the piston with saidring against said opposite side of the groove.
 2. The ram of claim 1,wherein said piston has a recess indented inwardly from its said endwhich faces said end wall, and said fluid passage means includes saidrecess.
 3. The ram of claim 1, which further comprises metering passagecommunicating with said end of said piston and joining with the side ofthe piston at a point located toward the piston''s opposite end from thelocation of said groove.
 4. The ram of claim 3, wherein a fluidtightsealing annulus is provided which extends about said piston and which islocated toward said opposite end of the piston from the point where saidmetering passage means joins with the side of the piston.
 5. Adouble-acting ram as claimed in claim 1, which includes an opposite endwall closing off the opposite end of the cylinder, said piston having anend opposite its said one end which faces said opposite end wall,another annular groove extending about the piston adjacent saidpiston''s opposite end, said other groove including one side which isadjacent and an opposite side which is remote from said opposite endwall, another ring mounted within said other groove with the peripherythereof disposed radially outwardly of the periphery of the piston andagainst the inside of the cylinder, said other ring being looselymounted in said other groove whereby it is axially shiftable within saidother groove, a second fluid passage means connecting said opposite endof the piston with said other groove, and another port in the ramcylinder for the supply and exhaust of fluid to said ram, said otherport communicating through said other groove and said second fluidpassage means with said opposite end of the piston when said piston isadjacent said opposite cylinder end wall and said ring is against saidone side of the other groove, said port being closed off from saidopposite end of the piston with said ring against said opposite side ofsaid other groove.
 6. The ram of claim 5, which further comprises afluidtight sealing annulus extending about the piston at a locationintermediate said first and said other groove.
 7. The ram of claim 6,which further comprises metering passage means communicating with saidopposite end of the piston and joining with the side of the piston at apoint located between said annulus and said other groove.